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United States Patent |
6,042,348
|
Aakalu
,   et al.
|
March 28, 2000
|
Protective shutter assembly for a forced air cooling system
Abstract
A protective shutter assembly for a fan of a forced air cooling system
includes lightweight shutter members mounted for pivoting motion about
vertical axes. When the fan is operative, its shutter members are pivoted
in a first direction to expose the fan and allow air to be exhausted
therefrom. When a fan is inoperative, its shutter members pivot in a
second direction toward the fan and overlap to prevent air from being
reversely drawn into the fan.
Inventors:
|
Aakalu; Nandakumar G. (Suffern, NY);
Maurice; Woodly (Irvington, NJ)
|
Assignee:
|
Lucent Technologies Inc. (Murray Hill, NJ)
|
Appl. No.:
|
075479 |
Filed:
|
May 11, 1998 |
Current U.S. Class: |
417/423.5; 361/695; 417/297; 417/427 |
Intern'l Class: |
F04B 017/00; H05K 007/20 |
Field of Search: |
417/286,423.1,297,427,423.5
361/695
|
References Cited
U.S. Patent Documents
1532635 | Apr., 1925 | Osbun | 361/695.
|
4495545 | Jan., 1985 | Dufresne et al. | 361/695.
|
4594940 | Jun., 1986 | Wolbrink et al. | 454/346.
|
4648007 | Mar., 1987 | Garner | 361/695.
|
5412534 | May., 1995 | Cutts et al. | 361/695.
|
5773755 | Jun., 1998 | Iwatare | 174/17.
|
Primary Examiner: Freay; Charles G.
Assistant Examiner: Evora; Robert Z.
Claims
What is claimed is:
1. A forced air cooling system for heat generating equipment comprising:
at least two fans, each of said fans having an air inlet end and an air
outlet end;
a structure for supporting said at least two fans so that said at least two
fans when operative draw air into their air inlet ends from a common
enclosed space adjacent said equipment and exhaust the drawn air from
their air outlet ends away from said common enclosed space in a
substantially horizontal direction; and,
at least two protective shields each associated with a respective one of
said at least two fans, each of said at least two shields being adjacent
and overlying the air outlet end of its respective fan, each of said at
least two shields including a pivotally mounted solid member arranged (a)
to pivot away from the air outlet end when the respective fan is operative
and air is exhausted outwardly from its air outlet end and (b) to pivot
toward the air outlet end to cover the air outlet end when the respective
fan is inoperative and air is drawn into its air outlet end,
each of said at least two protective shields comprise a plurality of
substantially planar solid members pivotally disposed across and
intersecting with the outlet, in an equally spaced and overlapping louver
arrangement, said solid members are arranged to pivot each about a
respective one of a plurality of parallel axes.
2. The system according to claim 1 wherein each of said at least two
protective shields is arranged to pivot about a respective vertical axis.
3. The system according to claim 1 wherein said plurality of parallel axes
are vertical.
4. In combination with a forced air cooling system having at least two
motor driven fans drawing air from a common enclosed space and exhausting
the drawn air to an ambient outlet, at least two protective shutter
assemblies each associated with a respective one of said fans, each of
said shutter assemblies comprising:
a substantially planar solid member; and,
a mounting structure for said solid member between the respective fan and
the ambient, the mounting structure including a pivot holding the solid
member, and being so arranged that the solid member (a) pivots in a first
direction to expose the respective fan when the respective fan is
operative to exhaust air and (b) pivots in a second direction to cover the
respective fan when the respective fan is inoperative to prevent air from
the ambient from being drawn past the respective fan into the common
enclosed space;
each of said at least two protective shutter assemblies includes a
plurality of substantially planar solid members and the mounting structure
includes a plurality of parallel pivots each for holding a respective one
of the plurality of solid members so that the solid members are all
pivotally disposed across and intersect the outlet, in an equally spaced
and overlapping louver arrangement.
5. The assembly according to claim 4 wherein the fans are arranged so that
exhausted air is directed substantially horizontally and said mounting
structure is arranged so that said solid member pivots about a vertical
axis.
6. The assembly according to claim 5 wherein the spacing between adjacent
ones of said parallel pivots is such that a person's finger is prevented
from passing therebetween.
Description
BACKGROUND OF THE INVENTION
This invention relates to a forced air cooling system and, more
particularly, to a protective shutter assembly for the fans of such a
system.
Electrical equipment which generates heat is often provided with at least
two motor driven fans which draw air from a common enclosed space
surrounding the electrical equipment and exhaust the drawn air to the
ambient. Each of the fans is typically covered by a wire grid to protect a
person's fingers from the fan blades. If one of the fans should fail, it
acts as an air inlet for the functioning fan(s), thereby bypassing the
normal cooling path and adversely impacting the cooling of the heat
generating equipment. It would therefore be desirable to provide structure
which prevents the aforedescribed cooling air bypass when a fan fails.
SUMMARY OF THE INVENTION
In accordance with the principles of this invention, there are provided
protective shutter assemblies each associated with a respective fan in a
forced air cooling system having at least two motor driven fans drawing
air from a common enclosed space and exhausting the drawn air to the
ambient. Each shutter assembly comprises a substantially planar solid
member and mounting structure for the solid member between the respective
fan and the ambient. The mounting structure includes a pivot holding the
solid member, and being so arranged that the solid member (a) pivots in a
first direction to expose the respective fan when the respective fan is
operative to exhaust air and (b) pivots in a second direction to cover the
respective fan when the respective fan is inoperative to prevent air from
the ambient from being drawn past the respective fan into the common
enclosed space.
In accordance with an aspect of this invention, the fans are arranged so
that exhausted air is directed substantially horizontally and the mounting
structure is arranged so that the solid member pivots about a vertical
axis.
In accordance with another aspect of this invention, the assembly includes
a plurality of substantially planar solid members and the mounting
structure includes a plurality of parallel pivots each for holding a
respective one of the plurality of solid members so that the solid members
overlap when they pivot in the second direction to cover the respective
fan.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing will be more readily apparent upon reading the following
description in conjunction with the drawings in which like elements in
different figures thereof are identified by the same reference numeral and
wherein:
FIG. 1 is a perspective view, partially broken away, showing prior art
electrical equipment having a forced air cooling system;
FIG. 2 schematically depicts air flow in a fully functioning prior art
forced air cooling system of the type shown in FIG. 1;
FIG. 3 schematically depicts air flow in the system of FIG. 2 when one of
the fans is not operative;
FIG. 4 is a schematic top plan view of a forced air cooling system
including shutter assemblies according to the present invention, wherein
both illustrated fans are properly functioning; and
FIG. 5 is a view similar to FIG. 4 wherein one of the fans is not operative
.
DETAILED DESCRIPTION
Referring now to the drawings, FIG. 1 shows illustrative prior art heat
generating electrical equipment, designated generally by the reference
numeral 10. The equipment 10 includes a plurality of heat conducting fins
12 arranged in parallel columns to form a plurality of vertical channels
14. The fins 12 are covered by a cover member 16 so that they are situated
within an enclosed space. Below the cover member 16, and communicating
with the enclosed space, is a fan assembly 18 to provide forced air
cooling of the electrical equipment 10. Illustratively, the fan assembly
18 includes five fans 20, positioned side-by-side, and arranged to draw
air from the enclosed space under the cover member 16 and to exhaust the
drawn air to the ambient in a substantially horizontal direction. Thus,
cooling air is drawn by the fans 20 downwardly through the channels 14 to
cool the electrical equipment 10. Each of the fans 20 is covered by a wire
grid 21 to protect a person's fingers from the blades of the fans 20.
FIG. 2 schematically illustrates the air flow pattern in equipment of the
type shown in FIG. 1 wherein there are two functioning fans 22, 24,
illustratively arranged side-by-side. The fans 22, 24 draw air from a
common enclosed space under the cover member 26. Thus, as shown by the
broken arrows 28, air is drawn downwardly behind the cover member 26 and
through the vertical channels 14 between the fins 12 (FIG. 1) to the inlet
ends of the fans 22, 24. As shown by the solid arrows 30, the drawn air is
then exhausted from the outlet ends of the fans 22, 24 away from the
enclosed space in a substantially horizontal direction.
FIG. 3 illustrates the air flow when the fan 22 is not operative. In this
case, operation of the fan 24 draws air reversely through the fan 22 and
into the common enclosed space behind the cover member 26, as shown by the
arrow 32. This air passes behind the cover member 26 to the inlet end of
the fan 24, as shown by the broken arrows 34 and is exhausted by the fan
24, as shown by the arrow 36. Since the fan 24 has a limited capacity, a
large portion of its capacity is taken up by air which is drawn reversely
through the fan 22, thus reducing the amount of air which can be drawn
past the fins 12 (FIG. 1) and reducing the cooling capacity of the
equipment.
FIGS. 4 and 5 are schematic top plan views of a forced air cooling system
incorporating structure according to the present invention. As shown,
there are a pair of fans 38, 40, each having an air inlet end 42, 44,
respectively, and an air outlet end 46, 48, respectively. The fans 38, 40
are supported on the brackets 50 so that when operative, they draw air
into their air inlet ends 42, 44 from a common enclosed space 52 which is
adjacent the heat generating equipment. The drawn air is exhausted from
the air outlet ends 46, 48 away from the space 52 in a substantially
horizontal direction. Associated with each of the fans 38, 40 is a
respective shutter assembly, or protective shield, 54, 56. Each of the
shutter assemblies 54, 56 is adjacent to and overlies the air outlet end
46, 48 of its respective fan 38, 40.
Construction and operation of only the shutter assembly 54 will given
herein, it being understood that the shutter assembly 56 is identical
thereto. Thus, the shutter assembly 54 includes a plurality,
illustratively three, of solid members 58 which are substantially
rectangular in shape and are mounted along one edge to a respective pivot
60. Preferably, the pivots 60 are parallel and vertically aligned. The
spacing between the pivots 60 should be such that a person's finger cannot
extend therebetween and is thus protected from contact with the fan
blades.
The solid members 58 are of lightweight construction, illustratively being
made from stamped aluminum. As shown in FIG. 4, when the fans 38, 40 are
functioning, air drawn into their inlet ends 42, 44 and exhausted from
their outlet ends 46, 48 causes the solid members 58 to pivot in a first
direction away from the air outlet end and thus expose the fan. Usually,
the fan pressure is low, so by using lightweight solid members 58 mounted
on vertical pivots 60, gravitational effects are avoided.
As shown in FIG. 5, should the fan 38 become inoperative, the fan 40 will
continue to draw air from the enclosed space 52 and will cause there to be
a lower pressure at the air inlet end 42 of the fan 38 than in the
ambient. Accordingly, this pressure differential will act on the solid
members 58 of the shutter assembly 54 and cause the solid members 58 to
pivot toward the air outlet end 46 of the fan 38. The solid members 58 are
dimensioned so that they overlap when they are pivoted toward the air
outlet end 46 of the fan 38. This almost entirely closes off the air
outlet end 46 from the ambient to prevent air from being drawn reversely
through the fan 38 and adversely effecting the cooling of the heat
generating equipment. Thus, in effect, the shutter assembly 54 functions
both as a protective shield for a person's fingers and as a one way valve
for air flow.
Accordingly, there has been disclosed an improved protective shutter
assembly for fans of a forced air cooling system. While an exemplary
embodiment of the present invention has been disclosed herein, it is
understood that various modifications and adaptations to the disclosed
embodiment will be apparent to those of ordinary skill in the art and it
is intended that this invention be limited only the scope of the appended
claims. Thus, while the fans have been illustrated as being side-by-side,
it is understood that this relative positioning is not a necessary part of
the present invention, which requires that the fans draw air from a common
enclosed space.
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